Ah, so the Blackbirds were actually extra atmospheric interceptors that the government pretended were reconnaissance aircraft to prevent the inevitable panic if the general public realised we were at war with alien invaders?

Imagine if they did enter service as a silver bullet force, like the F-22, but were also made available to the closest of allies.

I recall reading that a substantial amount of titanium used in the SR-71s fabrication was sourced from the USSR, a production run of two to three hundred F-12s would need much more titanium and hence much greater effort in exploiting western reserves and developing more efficient and affordable extraction techniques, perhaps led by Australia's CSIRO, the Australian government being keep to exploit natural reserves and further strengthen strategic defence ties to the US.

End result, a cheaper but still expensive F-12 built in reasonable numbers (1000+?), attack / penetration versions developed. And of course this being me, an Australian silver bullet force of two fighter and one attack squadrons.

Given the similarities between the original J58-P-2 and the Gyron, I could see a Gyron Major with the same changes as made to produce a J58-P-20 as fitted to the various A-12/F-12/SR-71 variants, and fitted to a British variant (SR-71K?).